In the rich text editor:
@Eee
In a comment:
[Eee](https://chowlings.com/user/Eee)
For Names and Avatars:
In the rich text editor:
%Eee
In a comment:
[![Eee's Avatar](https://chowlings.com/images/avatars/default.jpg)](https://chowlings.com/user/Eee) [Eee](https://chowlings.com/user/Eee)